fusca3: A Heterochronic Mutation Affecting Late Embryo Development in Arabidopsis.

Molecular studies of late embryogenesis and seed development have emphasized differential gene expression as a means of identifying discrete stages of embryogenesis. Little has been done to identify factors that regulate the length of a given developmental stage or the degree of overlap between adjacent developmental programs. We designed a genetic screen to identify mutations that disrupt late embryo development in Arabidopsis without loss of hormonal responses. One such mutation, fusca3 (fus3), alters late embryo functions, such as the establishment of dormancy and desiccation tolerance, and reduces storage protein levels. fus3 cotyledons bear trichomes, and their ultrastructure is similar to that of leaf primordia. Immature fus3 embryos enter germinative development, and the shoot apical meristems develop leaf primordia before seed desiccation begins. The cotyledons resemble leaf primordia, yet retain some cotyledon characteristics; thus, cotyledon- and leaf-specific functions are expressed simultaneously. Together, these observations are consistent with a heterochronic interpretation of the fus3 mutation.

Etodolac kinetics in the elderly.

The effects of age and chronic dosing on the pharmacokinetics of the anti-inflammatory drug etodolac were evaluated in healthy young subjects, healthy elderly subjects, and elderly patients with osteoarthritis. After either single or chronic (7 days) dosing, both the healthy elderly subjects and the elderly patients with osteoarthritis had values for etodolac peak concentration, time to reach peak concentration, the AUC from 0 to 24 hours, elimination t1/2, and free fraction that did not differ significantly from those in the young (control) subjects. Despite the expected increases in the peak concentration and AUC from 0 to 24 hours for all groups after chronic dosing, there were no changes in etodolac free fraction, time to peak concentration, or t1/2. Because significant accumulation of etodolac was not observed in our elderly participants, adjustment of dosage when elderly subjects receive etodolac therapy is not indicated.

Tolrestat kinetics.

The kinetics of tolrestat, a potent inhibitor of aldose reductase, were examined. Serum concentrations of tolrestat and of total 14C were measured after dosing normal subjects and subjects with diabetes with 14C-labeled tolrestat. In normal subjects, tolrestat was rapidly absorbed and disappearance from serum was biphasic. Distribution and elimination t 1/2s were approximately 2 and 10 to 12 hr, respectively, after single and multiple doses. Unchanged tolrestat accounted for the major portion of 14C in serum. Radioactivity was rapidly and completely excreted in urine and feces in an approximate ratio of 2:1. Findings were much the same in subjects with diabetes. In normal subjects, the kinetics of oral tolrestat were independent of dose in the 10 to 800 mg range. Repetitive dosing did not result in unexpected cumulation. Tolrestat was more than 99% bound to serum protein; it did not compete with warfarin for binding sites but was displaced to some extent by high concentrations of tolbutamide or salicylate.

Concomitant etodolac affects neither the unbound clearance nor the pharmacologic effect of warfarin.

Potential interactions between the nonsteroidal anti-inflammatory etodolac and the anticoagulant warfarin were studied in 18 healthy subjects by use of a randomized, three-period crossover design. Each treatment lasted 2 1/2 days and consisted of warfarin, etodolac, or both drugs. Prothrombin time was determined daily during each warfarin period to measure pharmacologic effect. Total serum concentration and unbound fraction of both drugs were determined over the dose interval after the last dose of the study drug(s). Concomitant etodolac did not affect the prothrombin time response or the unbound clearance of warfarin. During concomitant etodolac administration, the median peak concentration of total warfarin was significantly decreased by 19% (p = 0.005), median total clearance was significantly increased by 13% (p = 0.0123), and the unbound fraction tended to increase (median unbound fraction of warfarin, 1.245% with etodolac and 1.045% without etodolac; p = 0.0979; not statistically significant). These observations suggest a small displacement of warfarin from serum protein by etodolac or a metabolite of etodolac. No etodolac pharmacokinetic parameter was significantly affected by concomitant warfarin administration. Thus etodolac does not appear to alter the unbound clearance of warfarin or augment its pharmacologic effect. Nevertheless, it is prudent that clinical monitoring be done for individuals taking these two compounds concomitantly.

The pharmacokinetics of etodolac in serum and synovial fluid of patients with arthritis.

The pharmacokinetics of etodolac have been evaluated in five patients with arthritis given 200 mg etodolac, twice daily, at 12-hour intervals, for 7 days. Albumin and total protein concentrations were markedly lower in synovial fluid than in serum, and etodolac free fraction was significantly higher. Etodolac readily penetrated into the synovial fluid, and in the postdistributive phase the concentration of free etodolac (i.e., the drug responsible for pharmacologic activity) remained higher than that in serum at all times. No differences in the half-life of etodolac elimination were noted.

The effect of renal disease on tolrestat pharmacokinetics.

Many patients with diabetes who may benefit from treatment with tolrestat, a new aldose reductase inhibitor, will have nephropathy. Therefore the effect of renal dysfunction on the pharmacokinetics of tolrestat was evaluated in eight subjects maintained on hemodialysis, 11 subjects with partial renal impairment (creatinine clearance values ranging from 14 to 80 ml/min/1.73 m2), and eight normal subjects. Each subject received a single oral dose of 200 mg tolrestat. Blood and urine samples were collected during a 48-hour period, and tolrestat concentrations were measured by HPLC. Renal dysfunction had no apparent effect on the rate of absorption or volume of distribution of tolrestat. However, tolrestat clearance was significantly reduced from 30 +/- 3 (SD) ml/hr/kg in the normal subjects to 15 +/- 5 ml/hr/kg in the subjects receiving dialysis, and tolrestat half-life was prolonged from 11 to 16 hours. Therefore a reduction in tolrestat dose is suggested for patients with severe renal impairment.

Pharmacokinetics of the aldose reductase inhibitor tolrestat: studies in healthy young and elderly male and female subjects and in subjects with diabetes.

Tolrestat is an aldose reductase inhibitor undergoing clinical trials in diabetic subjects that may reduce the severity of chronic tissue damage associated with hyperglycemia. These studies were conducted to evaluate the pharmacokinetics of tolrestat in healthy young and elderly male and female subjects and in young and elderly subjects with diabetes. The drug was administered in a multiple-dose regimen, and steady-state parameters were obtained. There were no important gender-related differences, but mean values for apparent oral clearance, renal clearance, and corresponding unbound parameters were significantly lower for the elderly healthy subjects than for the young healthy subjects. The drug is highly bound to plasma proteins, and the unbound fraction (0.75%) did not differ among the subjects. The results from young and elderly diabetic subjects suggest that diabetes per se has no influence on tolrestat disposition but that there is an age-related reduction in apparent oral clearance (30 versus 18 ml/hr/kg) and a corresponding increase in the minimum steady-state plasma concentration (1.2 versus 1.9 micrograms/ml). These data indicate a possible need to reduce the dose of tolrestat in elderly subjects, assuming the same concentration-response relationship.

Pharmacokinetics and disposition of the lipid-lowering drug acifran in normal subjects and in patients with renal failure.

The pharmacokinetics and metabolic fate of the antihyperlipidemic drug acifran were assessed after a single oral dose of the 14C-labeled drug to healthy male volunteers. Peak serum acifran and radioactivity concentrations were attained 1 to 2 hours after dosing, and the drug was eliminated with a half-life of 1.6 hours. Virtually all of the recovered dose was excreted in the urine. All of the serum and urinary radioactivity was caused by unconjugated acifran. In patients with moderate chronic renal failure, the binding of acifran to plasma proteins was decreased, and the plasma concentrations of total and unbound drug were greater than those of healthy subjects. Renal failure substantially reduced the plasma and renal clearance of total and particularly of unbound acifran, moderately reduced its volume of distribution, and increased its elimination half-life from 1.4 to 1.7 hours to 5.7 hours. The results show that acifran is very well absorbed, is rapidly eliminated, is excreted in the urine, and does not undergo any detectable biotransformation in healthy human subjects.

Comparative bioavailability of propranolol: twice-daily versus four times-daily administration.

Nineteen healthy male volunteers were given daily 160 mg propranolol hydrochloride in divided doses, either four 40-mg tablets or two 80-mg tablets, and the plasma propranolol concentration profiles were compared after one and seven consecutive days of drug administration. The results indicate that the relative rate and extent of propranolol absorption were greater after 80 mg given twice daily than after 40 mg given four times per day. Both differences were statistically significant at steady state attained with the seven-day treatment. The variability in the areas under the concentration-time curves of propranolol appeared to be smaller after the 80-mg twice-a-day dosing schedule. The results are in accordance with the observed therapeutic equivalence of the two dosing regimens.

Pharmacokinetics of cetamolol in hypertensive patients with normal and compromised renal function.

The efficacy, safety, and pharmacokinetic parameters of a 30-mg oral dose of cetamolol hydrochloride (Betacor), a new synthetic cardioselective beta-adrenoceptor antagonist, with intrinsic sympathomimetic activity, were evaluated by studying 32 hypertensive patients with normal renal function or different degrees of renal impairment. After administration of cetamolol, serial blood and urine sample collections, as well as vital sign determinations for the next 48 hours, were performed in all patients (with the exception of urine collection, which was not possible in hemodialysis patients). Results indicate that cetamolol's pharmacokinetic parameters are significantly changed in patients who have moderate or severe renal impairment. Specifically, as the severity of renal impairment increased, the maximum serum concentration (Cmax) and the area under the serum concentration-time curve (AUC) increased, whereas the renal clearance (CLR), urinary excretion, and total body clearance (CL) decreased. Additionally, significant direct or inverse correlations for AUC, CL, CLR, and urinary excretion with creatinine clearance (CLCR) were demonstrated. In the subjects with mild renal impairment, the trends toward changes in the cetamolol pharmacokinetic parameters were evident, though small and not statistically significant. Although anuric, patients on hemodialysis still retained the ability metabolically to clear cetamolol at a rate of about one-third of that found in normal subjects. Reductions in blood pressure and heart rate also were found to be greater and more prolonged as the severity of renal impairment increased. There were no adverse drug or toxic effects noted in any of the study patients. Based on these findings, dosing recommendations are suggested for patients who have compromised renal function because of the effects of renal function on the pharmacokinetics of cetamolol.

Comparative pharmacodynamics and pharmacokinetics of conventional and long-acting propranolol.

This investigation was conducted to compare the pharmacokinetic and pharmacodynamic effects of single and multiple doses of conventional propranolol and long-acting propranolol in healthy human volunteers. Two double-blind, randomized, double-crossover, Latin square studies were carried out. One study evaluated long-acting propranolol 160 mg/d, conventional propranolol 40 mg qid, or placebo for seven days in 24 men. The other study compared long-acting propranolol 80 mg/d, conventional propranolol 20 mg qid, or placebo for seven days in 27 men. At specific times after the administration, blood samples were obtained, and heart rate and blood pressure were measured; exercise tests were done both on the first day and at steady state (day 7). In both studies, the area under the plasma propranolol concentration-time curve and the peak concentration were significantly less (P less than .0001) after the administration of long-acting propranolol compared with conventional propranolol on both day 1 and day 7; in addition, the elimination half-life was longer after administration of the long-acting preparation (9 hr) compared with that following the conventional dosage form (4 hr). Both conventional and long-acting propranolol significantly decreased the exercise heart rate at each of the selected time points (P less than .05) compared with placebo. Reduction in exercise heart rate was greater with conventional propranolol than with the long-acting formulation, but the differences were not statistically significant, when exercise was performed only at trough levels of the conventional drug. The decreases in exercise heart rate were correlated with plasma propranolol concentrations.

Butriptyline: improved gas-liquid chromatographic method using a nitrogen-phosphorus detector for its determination in serum.

We report a sensitive and specific method for the determination of butriptyline concentrations in serum by gas-liquid chromatography with a nitrogen phosphorus detector. The detection limit is 2 ng/ml, based on 3 ml of serum or plasma. The method has been validated in human volunteers receiving a single oral dose of 75 mg butriptyline hydrochloride.

A gas-liquid chromatographic method for the determination of butriptyline in serum.

1. A gas-liquid chromatographic (GC) method for the analysis of butriptyline in serum has been development. Quantitation is based on the peak height ratio between butriptyline and promazine used as internal standard. A triple partition provides a "clean" extract. A detection limit of 10 ng/ml is achieved. 2. The usefulness of the method has been demonstrated in bioavailability studies in dogs.

A high pressure liquid chromatographic determination of p-chlorophenoxyisobutyric acid and its comparison to a GLC and an ultra violet spectrophotometric method.

A rapid and reliable method for the determination of clofibric acid in serum using high pressure liquid chromatography has been elaborated and compared to a GLC and UV spectophotometric procedure. The limit of detection of the method is 0.3 micrograms/ml.

A method for the analysis of chlorhexidine in serum.

A colorimetric method for the determination of chlorhexidine in serum or plasma has been elaborated; the limit of detection of the method is 25 ng/ml, based on 10 ml of serum or plasma.

An automated method for the analysis of nicotinic acid in serum.

Rational antihyperlipemic therapy based on the use of nicotinic acid and its derivatives and/or combinations demands a rapid and reliable method for monitoring nicotinic acid blood levels. To this end, an automated colorimetric method for the analysis of nicotinic acid in serum has been elaborated. For serum from rats, dogs and man given p.o. nicotinic acid or 3-pyridine methanol, the method is greater than 90% specific for nicotinic acid. The limit detection for nicotinic acid is 2 microgram/ml based on 0.15 ml of serum or 0.3 microgram/ml based on 1.5 ml of serum.

A gas-liquid chromatographic determination of p-chlorophenoxyisobutyric acid and its comparison to an ultra violet method.

1. A gas-liquid chromatographic procedure for the determination of p-chlorophenoxyisobutyric acid (CPIB) has been elaborated and compared to the UV spectrophotometric procedure of Barrett and Thorp. 2. Both methods are specific when used to determine CPIB levels in normal sera from laboratory animals or humans treated with clofibrate (Atromid-S). Serum from patients treated with other drugs or abnormal sera from patients affected with a variety of diseases will often contain high and fluctuating levels of non-specific UV absorbing substances and this usually precludes the use of the UV procedure. 3. The GLC method is also applicable to the analysis of CPIB in urine samples.

Phototoxic and photochemical properties of sanguinarine.

Sanguinarine, a commercial drug exhibiting antimicrobial and antitumor properties, was studied with respect to its basic photochemical characteristics and also with regard to its phototoxicity to mosquito larvae (Aedes atropalpus). Sanguinarine proved to be clearly phototoxic to larvae, with an LD50 of 0.096 mg/mL with near UV exposure as compared with 23.3 mg/mL without. Flash photolysis experiments enabled the study of the triplet state of sanguinarine to be undertaken. Quenching by oxygen occurs with a rate constant of 6 x 10(9) M-1s-1 and time-resolved emission studies indicate that sanguinarine produces a significant amount of singlet oxygen (phi delta = 0.16) as does the isoquinoline alkaloid, berberine (phi delta = 0.25). These values represent the first direct quantitative measurements of photosensitization parameters of these compounds. Additionally, sanguinarine exhibits efficient electron donation properties, undergoing reaction with methyl viologen with a rate constant greater than 10(10) M-1s-1, but is a poor electron acceptor. Phototoxicity of sanguinarine can thus be explained in terms of its photosensitization properties.

Tolrestat pharmacokinetics in rat peripheral nerve.

The clinical efficacy of an aldose reductase (AR) inhibitor in diabetic polyneuropathy depends on its bioavailability at the site(s) of AR in peripheral nerves. Accordingly, the link between the concentration of the AR inhibitor, tolrestat, and the extent of its inhibition of the AR-catalyzed polyol production was investigated in sciatic nerves of galactosemic rats. Tolrestat was administered by gavage (1 x 150 mg/kg, or 5, and 15 mg/kg/day for 15 days to attain steady state as estimated from the 53-h half-life of tolrestat determined in rat nerve); subsequently, at six time intervals, ranging from 4 to 59 days, rats were given access for 4 days to a 20% galactose diet, and killed. At every time point, the composite tolrestat concentration in the nerve correlated with the percentage decrease in nerve galactitol (r = 0.857, p = 0.0015). Because the latter should reflect the extent of nerve AR inhibition by tolrestat, the concentration of "free" tolrestat available at the site(s) of AR in the nerve was estimated from the tolrestat concentration/percent AR inhibition plot obtained in vitro. The estimated amount of tolrestat present at the site(s) of nerve AR represented 0.4% of the composite tolrestat concentration measured in the nerve. The results support the view that the effectiveness of an AR inhibitor in peripheral nerve depends on its pharmacokinetics in the nerve, i.e., on its uptake, nonspecific binding to cellular constituents, and elimination.

Sensitive high-performance liquid chromatographic method for the determination of etodolac in serum.

A sensitive high-performance liquid chromatographic method for the determination of etodolac in serum was developed. The limit of detection was 0.2 microgram/ml. The specificity of the method was demonstrated by the lack of response obtained with a variety of control sera, sera spiked with etodolac congeners, and sera obtained from rats treated with a variety of other drugs.